What secrets are hiding in Mitt Romney's tax returns?

In his effort to be chosen as Sen. John McCain's running mate in the 2008 presidential election, Mitt Romney submitted 23 years of his tax returns to the McCain campaign — after which the senator and his staff rejected Mr. Romney and picked Sarah Palin instead. That decision ought to tell the American people something about Senator McCain's opinion of Mr. Romney as a potential president, about the contents of Mr. Romney's tax returns, or both.

The minimum requirement for anyone asking Americans to give them the authority and responsibility of the world's most powerful position is to be completely open about their careers, their policies and their financial interests. George Romney, Mitt's father and a former presidential candidate, published 12 years of his tax returns, explaining that seeing only one year's return could be deceptive. Despite both the family history and the nation's traditions, Mr. Romney has revealed just one year's complete return and part of another.

Many of Mr. Romney's fellow Republican leaders, as well as the media, have urged him to submit 10 or 12 years of returns immediately so he can get past this issue and go on the attack. The only reason a smart politician and Harvard lawyer would ignore such sound advice that he knows what's possibly in the returns — tax dodging, fraud, aggressive foreign tax schemes or other dishonesty — is even worse than the battering he's taking from friend and foe alike.

In the face of his refusal to disclose relevant information to the American electorate, it's neither unreasonable nor unfair to assume the worst unless the candidate comes clean and shares with the public the same information he gave to Mr. McCain and his staff.

Mr. Romney has been able to spin, flip-flop or otherwise avoid tough questions from both Republicans and Democrats, but it's difficult for anybody to spin 10 tax returns.